In today's economy, people exchange dozens of email messages everyday. Some of the email messages a person receives may contain important information. Other ones of the email messages a person receives may not seem important when they are received, but are later discovered to be useful. For this reason, people tend to retain email messages, even email messages of questionable importance, for long periods of time.
Retention of such email messages may cause storage problems for institutions providing email messaging services. For instance, institutions may have to purchase large and expensive data storage systems to store old email messages. In other instances, institutions may configure devices of end-users to store the users' old email messages. Storing email messages on users' computers may increase retrieval costs during e-discovery.